Apparatus for preventing interference in radiosignaling



March 30 1926. v R. A. WEAGANT I APPARATUS FOR PREVENTING INTERFERENCE IN RADIO SI GNALING Filed April 30, 1920 MQl" - V I Q I INVENTZi/L I BY A4 ATTQRNEY March 30, 1926.

1,518,490 R. A. WEAGANT APPARATUS FOR PREVENTING INTERFERENCE IN RADIOSIGNALING Filed A ril-sol 1920 4 Sheets-Sheet 2 ATTORNEY INVENTOR M March 30,1926; 1,518,490

R. A. WEAGANT APPARATUS FOR PREVENTING INTERFERENCE IN RADIOSIGNALDIG Filed April 30, 1920 4 Sheets-Sheet 3 4 INVEN'ITZEA/ bmw f w I March 30,1926.

R. A. WEAGANT APPARATUS FOR PREVENTING INTERFERENCE IN RADIOSIGNALING Filed April 30, 1920 4 Shets-Sheet 4 a. INVENTOR I M A ORNEY Patented Mar. 30, 1926.

UNITE-D STATES I 35,578,490 PATENT OFFICE.

ROY A. WEAGANT, orunw YORK, N. Y., Assieuon TO Ram oonronA'rion OF AMERICA, A conronarron or D LAWARE.

f APPARATUS roe PREVENTING m'rnnrnnnnon IN RADIOSIGNALING,

Application filed April 30, 1920. Serial No. 377,764.

To all whom it only concern:

Be it known that I, ROY ALEXANDER KVEAGANT, a citizen of the United States, and a resident of Douglas Manor, county of Queens, city and State of New York, have invented certain new and useful Improvements .in Apparatus for Preventing Interference in Radiosignaling, of which the following is a specification accompanied by drawings.

This invention relates to radio signaling. but more particularly to a method and apparatus-for preventing interference between stations. Y Next to theinterference of staticor strays, the most serious difficulty encountered, especially in long distance radio signaling, when a considerable number of stations are worked, is the interference between the stations themselves When the interfering station is 1000 orimore miles away, for instance, from the station at which reception is tak ing place, the use of different wave lengths has been most effective, but when the interfering station is comparatively near byand of great power, while the signal to be received is from a station at a great distance, r

trol wires ISIIlOii interfered with by ut1l1z the limitations of the capabilities of this method are serious, and the number of sta is comparatively small. v

The object of this invention is'to'secure a methodofworking and apparatus for overcoming and solving this interference prob lem and make it possible for any number of stations of any desired power, to work in a given area on any wave length desired. In accordance 'with my method, I am enabled to cancel the interference at a receiving station while permitting reception of the desired signals, by opposing substantially equal, and'opposite neutralizing effects to the interfering effects producedin the receiving circuits of. astation due to energy derived through the receiving. antenna from interfering waves. These neutralizing effects in the form of oscillations of'substantially' the same frequency aslthe interfering effects, set up neutralizing electromotive forces in the receiving circuits substantially equal and opposite to the inter-- fering electromotive forces produced in-the receivingcircuits' duel to the receiving. an tennae. i

tions which can be worked in a given area 1 *elie -medet peration,- I provide" meansfor directly affecting the receiving circuits at a receiving station by the signal energy. from an interfering transmitting station, and I adjust the receiving circuits until the electromotive force generated therein due to the directly applied energy from the said transmitting stationiis substantially equal and opposite to that produced, by signal energy derived from the antenna at the rcceivi ngstation due to interfering waves from the said transn'iitting station, and 1 thus neutralize theinte-rference, while permitting reception of the dev sired signals; In order to directlyapply the energy from the interfering station to'thereceiving circuits at the receiving station, I may employ land, wiresbetween the stations, electrlcally' connecting. or coupling the. trans- V mitting and receiving apparatus, and these land wires may be; an ordinary telegraph line or else they may conveniently be the wires used for'distant'control,xin-case the interfering station is controlled from the receiving station at which it is desired to receive signals.

' In either case the normal function ofthe land line or the distant coning them for the transmission of signal energy for the purposes mentioned. Another mode of operation in accordance with my invention, is to provide a, local source: of oscillations at the desired receiving'station, capable of generating 0scilla-. tions of the same frequency as the inter-- fering signals and coupling this oscillator to the receiving circuits, so that the oscillati'ons' aredirectly applied thereto. 'Means are also provided for controlling theoscillations in accordance with the transmission of signals from the interfering transmitting station, so that neutralizing oscillations start and opposethose picked up in thereceiving antenna from the interfering station at the instant of sending. The starting and stopping of'the opposing oscillations may be made automatically. simultaneous with .the: signals,- so that no effect is produced onltlhe' receiving circuits by the local oscillator when the sending key controllinga'n interfering station 15 open.

in the drawings Ilhave illustratedhsevoral preferred forms" of apparatus for care i-ng out myemetho'd' intwhich a diagrammatic representation of circuits and apparatus showing a land.

7 provided at the receiving station and autosuch a easel matically controlled by the operation of the transmitting key; and

Fig. 4 is a similar view of a modification in which a balancing antenna is shown at the receiving stationtogether with a local source of oscillations automatically controlled by interfering signal energy picked up by said balancing antenna.

Referring to the drawings, and 'atfirst more particularly to 1, A represents the antenna of a receiving station grounded at B and having the usual loading inductance C, variable condenser D and coupling coil E, which latter is coupled through coil F to a suitable receiver or receiving circuit G having, in this instanceythe vacuum tube detector H and telephones J with the necessary and desirable circuit connections well understood in the art without further description, A Y I The antenna of an interfering"transmitting station is represented diagrammatically at K. which may bea comparativelynear-by station. fifty miles distant from station A for instance, or farther away, orelse it .may' be closely adjacent" to station A in.

a case of simultaneous sendingand receiv ing from the same statioinbecause the principles of my invention are applioable to a 'As shown, the antenna K at the transmit-1 ting station is coupled through coupling coils L and O to the land wires P which, in this instance, may be ordinary telegraph wires or else they may constitute a separate circuit for the purpose of directly applying the transmitted energy to the receiving circuits G. The land circuit P is also coupled asshown through coupling coils Q, andR to the receiving'circuits G.

In the operation of the system, letit be assumed that "station A represents Belmar, New Jersey. which is receiving Garnarvon, Wales at ltOOOuneters, and that theinter tering station K represents New Brunswick;

Newrlersey, aboutiifty miles distant from Bclmar. also sending at 14000 meters. E.n-'

ergy is rec'eivechat the. receiving station from the transmittingfstation K by both the aerial- Jr and overth'e land wires P.

Q, R, of the land wires to 'tliereceiving c1rcu ts G istheutad usted until the electro- The coupling motive-1 force; ge erated in, the receivingcic' ergy over the land wires P from the transmitting station K, which will be very great relative to the static energy picked up, or compared to the signal energy which these wires will pick up from the distant Carnal von station, so that the coupling between coils Qand R at the receiving station, necessary to transmit suflicient of the signal from station K to balance the interfering signal energy picked up by the aerial A, will transmit none at all of the signal energy from the distant Carnarvon station and substantially no static. This is the all important necessary condition which ,no other method or arrangementheretofore known to me provides. The usual and customary arrangements employing balancing aerials are only operative when a line drawn between the interfering transmitting station and the receiving station forms a suitable right angle, with the line'to the station rom which it is desired to'rec'eive signals and even then no provision has been made" for-minimizing the interference or' static disturbances. g p I In my method of preventing interference, it makes no ditTerence-whatthe relative lo cations of the receiving and transmitting stations may be, nor what the wave length. Furthermore, in the arrangements shown herein, obviously static. eliminatingdevices may be used in accordance withthef methods eoases, 275,552, 275.553, 275,554,275s55, 275,556, 275,557. 373,929, and Patents Nos. 1,336,398, 1,356.751, 1,356,752, 1,389,800 and 1,853 002) and the balancing signal potential introduced into the receiving circuits without disturbance of the conditions for elimi nationof static. Suflicient energy for thepurposes of my invention maybe readily fed over the line .wires P, even although they cannot'be tunedexcept to harmonics, since so little energy is required to balance thatpicked up by the antenna A, which should be understood tobef asmall low aerial as now: used instead of high towers as;pre viou'sly used. 5 I i Any number of transmitting stations may he st ,and the same pair. oi? wiresniay be extended to each transmitting station and usecl't'o transmit opposing or, neutralizing effects to the receiving circuits atstation- A,

regardless of the wave length on which the connected, by land wires to the receiving preceding paragra 2 of the drawings in which K frequencies may be generated at the transmitting station in a well understood manner and the resulting beat frequency sent over the line, opposing it to the Same audio frequency current in the receiver.

It is easily possible for instance, for the small additional cost of a pair of land wires P perhaps 150 miles long, to permit the operation of an additional high power station in a given area, which would obviously we'll warrant the added'cost.

The arrangements referred to in the two phs areillustrated on Fig.

is an additional aerial supplied with high frequency current by twogenerators, the frequencies of which are adapted to produce beats. The aerial is coupled by means of transformer L, the secondary of which is connected to a rectifying circuit X in order to Obtainthe beat frequency currgents. These are -1m-' pressedon the line P, P which extends to the line P, P by means of the audiofrequency transformer L At the receiver an audio frequency transformer L is associated with the output circuit for impressing the beat frequency on thereceiver Gr.

Instead of a separate line P as shown in Fig. 1, the usual distant control wires P may be employed in carrying out my method as shown in Fig. 2, without in any way interfering with their operation for the .purpose of controlling a distant station K. In this case, S-represents the key at the interfering station K actuated by electromagnet T, in the circuit P, having the energizing battery U and controlling key V at the receiving station A. The control circuit P is coupled as shown at L, O, and Q, R, to the transmitter. and receiver respectively and each time that a signal is sent, opposing oscillations are set up in the receiver G as described. Another arrangement for car'- rying out the method is shown in Fig. 3 in a case in which the transmitting station K is controlled from the receiving station A by the control circuit P as before. A local source of oscillations, as for instance an oscillating vacuum tube W with suitable oscillating circuits, is provided at the receiving station A, capable of generating oscillations of the same frequency as the transmitting station K. As shown in this instance the grid circuit X of the vacuum tube WV is coupled into the receiving circuits G through coils Q and R, and the plate circuit Y of tube W is provided with the contact device Z controlled by electromagnet Z in the control circuit P closes, the contact device Z closes and oscillations from the tube V start and oppose those in the receiving circuits G picked up 'by the receiving antenna A from station K, and since the starting and stopping of hi terfering signals and neutralizing cscilla picked up by balancing antenna Each time that the key V and areused to opp so and neutralize those tions aresimultaneous,gno effect is produced on the receiving circuits ("Jr byxthe local" os- "cillator when the transmitting key V is ference. In this case A represents-a sepa-' rate balancing receiving antenna tuned to the particular interfering station from which interference is to be prevented. Antenna A is coupled-through coils E and F totlie grid circuit of a vacuum tube W having a. relay Z in its plate circuit, controlling the normally open contact device Z, in the plate circuit Y of the local oscilflatorlV, which is coupled as in 3 into the receiving circuits G of the-receiving station A. When the interferingsignal is A", the plate current in the vacuum tube V is reduced and the attraction of the relay Z for its armature isweakened, so that the contact device E closes its contacts under'the influence of the spring Z and in this way the local oscillator N is controlled. The oscillations of the local oscillator in this instance are to be the same as the interfering signal and are adjusted to oppose the said signal in the receiving circuits G. 1 r

I have found that the automatic operation of a vacuum tube relay on signals of the intensity of those-under consideration, is comparatively easily accomplished. and

has proved satisfactory. One such device or; V

arrangement as that shown in Fig. l, may-be provided for each interfering station and if these stations differ in. wave length by a coin-- paratively small amount, a large number of such interference preventing devices is perinissible, since in distinguishing between them, intensities of substantially the same order are dealt with, and not of a vastly different order, such as obtain when an attempt is made to receive from a far distant station and cut out the nearby interfering station'by tuning. The arrangement shown in Fig. f having a balancing antenna A. retains the same necessary fundamental characteristics of the land wire arrangements shown in the other figures, that is, it provides neutralizing currents of the same frequency, and generated simultaneously, as the interfering signal currents, which neutralizing currents are unaccompanied by static currents, other interfering signal currents, or any of the desired signal currents,

interfering signal currents picked up by the receiving antenna A. Thebala-ncing antenna arr n ement shown in ,Fig'. while not possessing substantially unlimited scope inJthe matter 013 wave le g a y land Wire arrangements, is on the other hand perhaps less expensive to install, and for equivalents Stitlllll the scope of my claims forming a part of this specification, Without departing from the spirit of my invention,

I claim and desire to obtain by Letters Patent the following:

1; In radio signaling t11e 1co1nbination of a receiving station and atransmitting station, means for generating t\VO, 1t1Cl1O frequency currents adapted to give a beat frequency, a v

circuit extendingfrom one station to the other adapted to couple the stations together and means for opposing beat frequency currents from said circuit to balance similar currents collected by the receiving station due to radiation from the transmitting station. 7 I v 2. In radio signaling systems the corn bination of a receiving station and a transmitting station means for generating two radio frequency currents adapted togive a beat frequency and a circuit extending from one station to the other for conveying said beat frequency currents to the receiver, and means for utilizing said beat frequency currents from said circuit to balance similar currents collected by the receiving station due to radiation from the transmitting station.

In testimony whereof I hereunto affix my 7 signature this 27th day of April,-1920.

' ROY A. WEAGANT. 

